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4hv.org :: Forums :: Electromagnetic Radiation
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Amateurs testing the EM-drive?

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Robert Clark
Sun Aug 13 2017, 12:32AM Print View
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This article gives a skeptical review of the experiments testing the EM-drive:

SCIENCE — NASA’s EM-drive still a WTF-thruster. New paper generates more noise than experimental thrust. CHRIS LEE - 11/22/2016, 5:17 PM


The researchers measured 128 micronewtons at 60 watts in vacuum. The problem is this thrust is very small so its difficult to rule out experimental errors. It's about the weight of a grain of sand.

They would be better off to redo the experiment at much higher powers. This actually isn't that hard to do. For instance common household microwave ovens put out 1,000 watts. So using six of these to get 6,000 watts you should get, if it is a real effect, in the range of 12.8 milliNewtons, or 12.8/9.81 = 1.3 milliKilograms-force = 1.3 grams-force. Forces at this weight range, about the weight of a cubic centimeter of water, are commonly measured in university labs.

In fact, this could probably tested by amateurs or university students. You can find amateur experimenters who have posted on the net various (dangerous!) experiments with microwave generators, magnetrons, taken from out-of-use microwave ovens:

Crazy Ukrainians Experiment with Microwaves.
Lindsay Handmer at 10:01 AM Jul 30 2014


The hardest part would be doing the EM-drive experiment in a vacuum though. Experiments showing positive results that have been done in air can be discounted because air currents can be the cause of the results observed.

For instance, here's an amateur doing a test of the EM-drive in air showing positive results. Numerous commenters to the video observed the results are unreliable because of the effect of heated air generating rising air currents:

EmDrive Test No.03 Success, I have thrust !!! - YouTube.


For an amateur though doing the experiment at high power in a vacuum chamber would be expensive because of the large size of the required vacuum chamber able to hold six 1,000 watt magnetrons. What might work is to use a waveguide to direct all the microwave energy to a small area that can be enclosed in a small vacuum chamber.

Bob Clark
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Sulaiman
Sun Aug 13 2017, 07:21AM
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I doubt that approach will help,
. getting 6 magnetrons to reliably phase-lock would require a lot of experimentation
. if the microvaves enter via a waveguide, this may add its own forces when carrying microwave power
(electromagnetic waves have momentum)
. 6 times more signal power from 6 times the weight and volume does not help much.

I have avoided playing with domestic magnetrons because the hv, and especially the rf, scare me,
and I've never had a use that outweighed these two concerns.
I used to work on a LINAC, using 4x 20 MW klystrons so I understand the physics a little,
here is a fairly recent document that I came across which may help a little


weioa04.pdf
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Robert Clark
Sun Aug 13 2017, 12:30PM
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Sulaiman wrote ...

I doubt that approach will help,
. getting 6 magnetrons to reliably phase-lock would require a lot of experimentation
. if the microvaves enter via a waveguide, this may add its own forces when carrying microwave power
(electromagnetic waves have momentum)
. 6 times more signal power from 6 times the weight and volume does not help much.

I have avoided playing with domestic magnetrons because the hv, and especially the rf, scare me,
and I've never had a use that outweighed these two concerns.
I used to work on a LINAC, using 4x 20 MW klystrons so I understand the physics a little,
here is a fairly recent document that I came across which may help a little


weioa04.pdf



Wow! Was that 100 MW total power continuous???

Some of these amateurs do experiments with multiple microwave generators combining their power:

TRIO OF MAGNETRONS POWER A MICROWAVE RIFLE. Dan Maloney October 22, 2016


Obviously if such is to be done in a university undergraduate lab it would have to be done under microwave expert supervision.

About the waveguide addings its own forces, the proposers of the EM-drive have considered that, and argue the results they've seen are orders of magnitude higher than that due to electromagnetic wave's momentum.


Bob Clark
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Dr. Slack
Sun Aug 13 2017, 05:01PM
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From what I read of the recent NASA vacuum experiments, a lot of the odd behaviour seemed to be due to the heating of the apparatus when under power, so unwanted/assymetrical torsion beam expansion rather than aircurrents. Without better experimental design, increasing the operating power would just increase the uncertainties. The interdigitated electrostatic calibration motor was quite capable of generating nice crisp torque steps, so there was no issue with sensitivity even down at that low power level. At its very least, the technique has to show torque/thrust monotonic with input power, and IIRC even that wasn't achieved.
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Hazmatt_(The Underdog)
Sun Aug 13 2017, 05:28PM
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Where is Bill Nye?

Isn't he supposed to "back this up" as "viable" technology, and call for the extermination of the "deniers"?

HAHAHHAH.
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DerAlbi
Mon Aug 14 2017, 05:44AM
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Robert, dont make a fool out of your self, this magnetron combining is fake as fuck. There is neither a appropriate power delivery system on their stick nor do they wear any eye protection.. which is the one body part thats most susceptible to RF heating.
Even if this thing does actually output RF energy, think again if those 4 batteries could ever deliver the power to even drive one magnetron to its full potential. The whole thing is a piece of shit (technically). I guess its fine if you call it art-work.
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Hazmatt_(The Underdog)
Tue Aug 15 2017, 01:50AM
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Yea a real setup would require those magnetrons be connected to some rectangular transition (it'd be huge, like 2" x 4" transition) then it would have to be coupled to a "Magic Tee" to sum the power.
All of which have to be silver plated, and even then it would get very hot.
The magnetrons would probably arc over constantly because they are not really being loaded, or would probably burn out faster because of reflected power.
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Sulaiman
Tue Aug 15 2017, 09:27AM
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I disagree;

They are generating short intense microwave pulses, so do not need huge batteries, and body-part damage due to heating is minimal.
(I'm of the opinion that there is more to rf damage to humans than just thermal effects, but I'm in the minority)

The horn antenna would load the magnetrons, it is a fairly efficient transmit antenna.

Magnetrons can be 'tuned' to phase lock, as they mentioned in the video.

The rf interference on the video gives a good clue to operation.

Would you walk back home through town wearing those outfits if you did not have to ?

I think that at least some of the video is real, and realistic.



I'm unable to do the math for the e.m. drive and I don't really understand it so I can't comment other than, whether it works or not, it will not make any difference to me in my little shed/workshop/lab/hideaway :)





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dexter
Tue Aug 15 2017, 10:29AM
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i don't get how the EM drive could ever generates trust... wouldn't the microwaves also bounce from the cone walls thus negating the top and bottom plates bounce inequality?
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DerAlbi
Tue Aug 15 2017, 11:42AM
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Sulamain.. which EM interference? You mean the video editing to simulate image sensor artifacts? All that why they press the trigger and simulate the thing would have some kind of recoil to make it more like shooting something?
One question: why would an image sensor be affected (and that only partially at a time, so you can still see the action for youtube!!), but the MP4 or whatever encoding processor works flawlessly... do you have ever seen a blocky corrupted encoded file? Guess what, it wouldnt look good on youtube.
Also have you ever seen an overloaded image sensor due to laser damage? Those image artefacts take a lot of time to vanish... also the purple nature of the artifacts is very interesting. Somehow the 2.45GHz of the magnetrons manage to excite only the blue and red sensors, but not the green ones which there are twice as much of....
Please, think critically; dont say its true because you wish it was..
And its not a short pulse. The duration of the simulated image sensor artefacts (if they were true) can last a second or more... 3 Magnetrons would have a power of at least 2kW... this means 2000J energy delivery.... you are on the forum long enough to know how a 2kJ energy storage looks like... i just wonder why you ignore the basics. unbelievable that one has to debunk a video like this on a forum like that. shouldnt happen.
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Hazmatt_(The Underdog)
Wed Aug 16 2017, 12:26AM
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Sulaiman,

They are using a very high voltage "taser" for their B+ on the magentrons, that is where the snapping noise is coming from.

When my capacitor bank flashed over (12nF 30kvdc doorknobs) on my SGTC, the video camera had the same effect, it was a mild form of EMP and caused distortion and loss of focus on the camera.
I believe all of the video interference is being caused by their taser, I think that's entirely plausible. Their scooter dying, their stereo dying, and other silly things are likely staged.
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Conundrum
Wed Aug 16 2017, 06:15AM
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Heh, used the same trick (old gas igniter) for my experiments!
Also noticed the EMP effect, did some damage to my camera this way once.
Actually its not always EMP, cameras try to focus "behind" the discharge as it is so bright, and the CCD tends to overload.
I found that the fix was to use an IR filter, alas the camera did not work for long.

EDIT:
Back in 2009 (possibly) I came up with a drive circuit which if minimally modified could power a magnetron in QCW mode.
I did not pursue any further research in this area because it had unforeseen dangerous side effects!
please PM me for more information.
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Robert Clark
Wed Aug 16 2017, 02:15PM
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Joined: Thu Feb 18 2016, 06:33AM
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dexter wrote ...

i don't get how the EM drive could ever generates trust... wouldn't the microwaves also bounce from the cone walls thus negating the top and bottom plates bounce inequality?



That is a complaint that has been leveled against its feasibility. I don't know much about it. It just seems to me it's something that can be easily confirmed or ruled out by amateur experimenters.

Bob Clark
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hen918
Wed Aug 16 2017, 04:09PM
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Joined: Wed Mar 20 2013, 08:20PM
Location: UK
Posts: 428
Robert Clark wrote ...

dexter wrote ...

i don't get how the EM drive could ever generates trust... wouldn't the microwaves also bounce from the cone walls thus negating the top and bottom plates bounce inequality?



That is a complaint that has been leveled against its feasibility. I don't know much about it. It just seems to me it's something that can be easily confirmed or ruled out by amateur experimenters.

Bob Clark


Well, the issue is not the ease of which a "EM-drive" can be made, but the requirements for testing it. The supposed thrust is so small, that without laboratory equipment and a laboratory environment nothing can be detected at all that can't be explained by other means. And even with the right resources those scientists are finding it a hard job to say yes or no.
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Robert Clark
Fri Aug 18 2017, 12:59AM
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DerAlbi wrote ...

Sulamain.. which EM interference? You mean the video editing to simulate image sensor artifacts? All that why they press the trigger and simulate the thing would have some kind of recoil to make it more like shooting something?
One question: why would an image sensor be affected (and that only partially at a time, so you can still see the action for youtube!!), but the MP4 or whatever encoding processor works flawlessly... do you have ever seen a blocky corrupted encoded file? Guess what, it wouldnt look good on youtube.
Also have you ever seen an overloaded image sensor due to laser damage? Those image artefacts take a lot of time to vanish... also the purple nature of the artifacts is very interesting. Somehow the 2.45GHz of the magnetrons manage to excite only the blue and red sensors, but not the green ones which there are twice as much of....
Please, think critically; dont say its true because you wish it was..
And its not a short pulse. The duration of the simulated image sensor artefacts (if they were true) can last a second or more... 3 Magnetrons would have a power of at least 2kW... this means 2000J energy delivery.... you are on the forum long enough to know how a 2kJ energy storage looks like... i just wonder why you ignore the basics. unbelievable that one has to debunk a video like this on a forum like that. shouldnt happen.


The effect should only be visible on the devices it was pointed at because of the waveguide. On the other hand if were only EMP effects it should have occurred also on the camera recording it for Youtube:

How to make a Microwave Gun.


Also, many amateurs have made "microwave guns" showing similar effects:



In regards to the energy content requirements, lithium rechargeable batteries get about 200 Wh/kg = 200*3,600 watt-seconds/kg = 720,000 J/kg. So if you needed 2,000 J per shot, you could get 360 shots from a kilo of lithium batteries, or 40 shots from 4 ounces of batteries.

Bob Clark

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DerAlbi
Fri Aug 18 2017, 05:27AM
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Joined: Sun Jun 06 2010, 02:20AM
Location: Dresden, Germany
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Please continue debunking your self... dont stop with the formulas there..
4 Batteries haave what voltage?
For a given Power thats how much current?
For that current, how big is the voltage drop over their wimpy cable and ESR of the batteries?
That limits the efficiency of the device how much?
Does the Magnetron work on the remaining voltage?
If they use a teaser as driver like others mention, does a teaser have enough power to power even one Magnetron? Why they need 3 of those?
So is this project then referable to as something that proves something could work, if the project itself is a technical nightmare? Or are you chasing a dream because someone bullshitted you on YT?


Why did you stop with your scientific explanation where the answer you got was the one you _wanted_ to get there is a lot coming afterwards. If the progress of humanity would depend on such kind of thinking we would back in the the religious middle ages. Thanks for your contribution No, honestly: bad habit. It serves no one. Neither you nor others.

Anyway. i think this is somewhat off topic. This is obviously not about whats believable, but its already decided that people want to believe.
Praise 4hvChurch.org.
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Robert Clark
Fri Aug 18 2017, 01:03PM
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The discussion of whether or not combining the magnetrons will be effective is not getting to the heart of the matter. I was suggesting combining six magnetrons only because it would give a nice round number of 1 gram-force for the alleged EM-drive effect. But of course university students and amateurs could just as easily measure a force of 1/6th that, which supposedly would come from a single 1,000 watt microwave.

You can get a used microwave oven from a thrift store for $25. I like the description given in the video I linked before for how to use the microwave's magnetron to do experiments with microwaves, including the safety precautions:

How to make a Microwave Gun.



Bob Clark
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Conundrum
Sun Aug 20 2017, 06:30AM
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Has anyone considered using multiple S/P piezotransformers in an array? As HVDC is needed this approach is plausible and would make for a very compact low RF noise device if HV diodes are used to separate transformers in a broadly similar way to a conventional IHVT.

PZTs or Rosen transformers are quite easy to drive and be bought new from Digikey among other suppliers or scavenged from broken laptops.
The output voltage is around 1.7KV off load so a 3S3P array would give 5.5KV at >400mA which is more than adequate for short pulses.
I believe that one major observation at cryogenic temperatures is that pulsed operation is far more efficient as chamber can be tuned to dissipate heat between pulses.
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Sulaiman
Sun Aug 20 2017, 08:19AM
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DerAlbi wrote ...

Please continue debunking your self... dont stop with the formulas there..
4 Batteries haave what voltage?
For a given Power thats how much current?
For that current, how big is the voltage drop over their wimpy cable and ESR of the batteries?
That limits the efficiency of the device how much?
Does the Magnetron work on the remaining voltage?
If they use a teaser as driver like others mention, does a teaser have enough power to power even one Magnetron? Why they need 3 of those?
So is this project then referable to as something that proves something could work, if the project itself is a technical nightmare? Or are you chasing a dream because someone bullshitted you on YT?


Why did you stop with your scientific explanation where the answer you got was the one you _wanted_ to get there is a lot coming afterwards. If the progress of humanity would depend on such kind of thinking we would back in the the religious middle ages. Thanks for your contribution No, honestly: bad habit. It serves no one. Neither you nor others.

Anyway. i think this is somewhat off topic. This is obviously not about whats believable, but its already decided that people want to believe.
Praise 4hvChurch.org.



Maybe you are looking at it based on incorrect assumptions;
I guess that energy is transfered from the battery to a storage capacitor, maybe at a few hundred volts, then transformed to a short high voltage pulse at high power, which powers the magnetrons, and maybe three in parallel forms a suitable load ?
but there other possibiities.

- just as I can make a 4" spark with a 1.4 W dc input sgtc ... at very low repetition rate.
Even though of short duration and incapable of cooking a frankfurter, these arcs easily destroy semiconductors.

The antenna horn is many wavelengths wide, hence it could be very directional.

I am not saying that everything in that video is real, but that it could be,
e.g. a short-circuit semiconductor can easily start a chain reaction that ends in catastrophic failure of a power supply for example - releasing the magic smoke.

P.S. another guess: the red filament lamp is part of the magnetron heater circuitry - these guys seem very inventive/pragmatic - good amateur scientists - and entertaining.

The truth probably lies somewhere between my hopeless naievety and your scathing scepticism.

Even when people seem ignorant it is best to be nice to them, or your own ignorance may be revealed,
this is a place for all to enjoy, and benefit from.

Have you experimented with pulsed magnetrons ?
(hint: the answer is either "no" or "yes but I did not understand what I was doing")

If you are incapable of understanding the above then you certainly should not try to understand, or comment on, EM drive.
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Robert Clark
Sun Aug 20 2017, 04:47PM
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Joined: Thu Feb 18 2016, 06:33AM
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Conundrum wrote ...

Has anyone considered using multiple S/P piezotransformers in an array? As HVDC is needed this approach is plausible and would make for a very compact low RF noise device if HV diodes are used to separate transformers in a broadly similar way to a conventional IHVT.

PZTs or Rosen transformers are quite easy to drive and be bought new from Digikey among other suppliers or scavenged from broken laptops.
The output voltage is around 1.7KV off load so a 3S3P array would give 5.5KV at >400mA which is more than adequate for short pulses.
I believe that one major observation at cryogenic temperatures is that pulsed operation is far more efficient as chamber can be tuned to dissipate heat between pulses.




Thanks for that info. Another project I'm investigating requires kilovolt voltages but at lightweight. Typical ferrite core transformers are too heavy for my application.

What's the weight of those PZT transformers able to deliver 1.7 KV*400mA = 680 watts?

Bob Clark
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Robert Clark
Sun Aug 20 2017, 04:55PM
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Joined: Thu Feb 18 2016, 06:33AM
Location:
Posts: 23
Sulaiman wrote ...

...
Even when people seem ignorant it is best to be nice to them, or your own ignorance may be revealed,
this is a place for all to enjoy, and benefit from.
...


Sulaiman, you are a very wise man, as your name suggests.

I've been engaging in internet discussion forums on various topics since the internet came to be for the general public.

An interesting phenomenon I've noticed over the years seems to hold true:

"The more harshly you ridicule someone else, the more likely you are to be wrong yourself."

Bob Clark
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